Anyone have any tips for identifying and washing gear that has poison ivy oil on it?

I've been out twice this year and developed really mild spots of poison ivy after both trips. The level of infection has me believe that I'm getting it from a piece of gear as if I had come into contact with an actual plant it would be much worse (I know from experience). I know the oil can stick around for over a year on gear. It's what gives people the impression the rash is spreading; it's not spreading, you're just coming into contact with it again on something. 

Anyone have any tips on how to figure out which gear is infected? It's showing up on my left forearm/wrist area and I can't think of what would have come into contact with the plant last year that would come off on just that spot. 

And how do I wash it? I've washed all sleeping stuffs and my boots. Maybe it's on my pack? Anyone have experience washing a pack? Any other ideas?